Railway car retarder



April 25, 1933 P. H. CRAGO RAILWAY GAR RETARDER Filed Jan. 16 1952 INVENTOR. Paul H. Cmgo. By Chm/ HLS ATTORNEY.

Patented Apr. 25, 1933 UNITED sates t me PAUL I-I. ORAGO, r WILKINSBURG, PE NsYLvANIa, AssrorNoa TO THE UNION swrron & SIGNAL COMPANY, or SWISSVALE, PENNSYLVANIA, A ooaroaATIoN or PENN- SYLVANIA RAILWAY GAR BETARDER Application filed Ian-nary 16, 1932. Serial No. 587,076.

'5 car. More specifically my invention relates to retarders of the type shown and described in Letters Patent of the United States No. 1,812,190, granted to lVolfgang Baseler on June 30, 1931. One feature of my invention 0 is the provision, in retarders of the type shown in the Baseler patent, of means for passing electric current through the wheels of a car for cooperation with the magnetic flux produced by the retarder magnets to increase the'retarding effect on the car.

I will describe one form of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a transverse sectional view showing one form of retarder embodying my invention. Fig. 2 is a side view of the retarder shown in Fig. 1.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference characters R and R designate the track rails of a railway track. Associated with the track rail R is a U-shaped electromagnet B the legs of which are located on opposite sides of the rail'and the pole pieces 5 of which are so disposed as to cooperate with the opposite faces of a car wheel W traveling on the rail. Ihe magnet is provided with the usual energizing winding A The magnet is pref- 5 erably so arranged that the pole pieces 5, 5

may move toward and away from each other, and so toward and away from wheel W according as the magnet is energized or deenergized as shown in the above mentioned Baseler Patent No. 1,812,190. As here shown, these pole pieces are arranged to slide horizontally on the two legs of the magnet. Other means may be provided, however, for permitting the pole pieces to move toward and away from the wheel V A similar magnet B is associated in a si1nilar manner with the track rail R and the two magnets B and B are oppositely disposed so that they cooperate simultaneously with the two wheels on a given axle D.

The windings A andA are supplied with alternating current from the secondary of'a transformer F, the primary of which is at times connected with a suitable source of current which is not shown in the drawing.

As shown in Fig. 2, the retarder will usually comprise a plurality of electromagnets B or B disposed along each track rail in parallel relation, the pole pieces 5 being common to all the magnets, so that these pole pieces constitute braking bars for cooperation'with the wheels of a car passing through the retarder.

As thus far described, the retarder is simi lar to that shown in the Baseler patent referred to hereinbefore. In accordance with my invention 1 connect a source of current across the two rails R and R for the purpose of producing current in the car wheels to cooperate with the magnetic flux produced by the magnets 13 and B As here shown, this source of current is the secondary of a transformer E, the primary of which is at times connected with a source of alternating current which is not shown in the drawing. One terminal of the secondary of this transformer isconnected with rail R and the other secondary terminal is connected with rail R It follows that when an axle and pair of wheels occupy the retarder, current will flow from the left-hand terminal, for.

example, of the secondary of transformer E, through rail R wheel W aXle D, wheel W and rail R to the right-hand terminal of the secondary of transformer E.

As shown in Fig. 1, the flux due to magnet B passes through wheel W in the direction indicated by the arrow G while the flux due to magnet B passes through the wheel W in the direction indicated by the arrow G Furthermore, the current produced by transformer E passes through the wheels and aXle in the direction indicated by the arrows 7. Thesedirections of flux and current are, of course, instantaneous relative When the directions of flux and current. are as just explained, then assuming that the car is moving toward the reader, as viewed in Fig. 1, the current in the wheels will cooperate with the fiux inthe wheels in such manner directions.

"as to tend to'retard the movement of the car. 1

tion.

The same result could be obtained by reversing the instantaneous relative direction of the flux in each magnet, and also reversing the instantaneous relative direction of the current through the car wheels andaxle.

It will be seen from the foregoing, that the axle D and the wheels and Vi, moving through the retarding magnets, produce the same effect as that which would be produced by moving a U-shaped wire through the length of the retarder with the two ends in contact with the two rails respectively, because current flows from one rail up to the axle and from the axle down to the other rail. Since the flux path is long, the current carrying pathcannot be forced completely out of the magnetic field as would be possible if a small magnetic pole were placed opposite the wheel. It is apparent that the force tending to prevent the movement of the axle and wheels in a direction toward the reader as viewed in Fig. 1, is proportional to tae vertical height of the magnetic field traversed by the wheel, the length of the retarder, the flux density, and the current flowing in the Wheels and axle; in other words, this force follows the usual laws for the force on a current carrying conductor moving in a magnetic field. The loss of efiiciency, due to magnetic flux flowing through the rail be tween the pole pieces 5 of either magnet, may, of course, be reduced to the minimum by using rails of non-magnetizable material, such for example, as maganese steel.

It should be noted that the tendency for the current path from point of contact of the wheel with the rail to the car axle to be forced backwardly into the rim of the wheel, is compensated by the fact that if the current were flowing in the rim of the wheel, the current line would be cutting a longer magnetic path than when the current flows directly through a radial path from the point of contact to the axle. This tendency of the current path to bend is therefore balanced at a point producing the least retardation. Furthermore, it will be seen from an inspection of Fig. 2 that the shortest possible path for the current through the magnetic field is the vertical path, and that the current could be deviated from this path only a very little without increasing the mechanical torque availablefor retardation of the car.

The supply of current to the transformers F and E may, of course, be controlled in any suitable manner, either manually or automatically, or both. The control of these currents forms no part of my present inven- Furthermore, he current supplied to the windings A and A and to the wheels and axles, may be direct current.

To produce the full retardation ordinarily desired, consideration must be given to the fact that the apparatus also produces retardation due to the eddy current efi'e'ct and the frictional effect, as set forth in the Baseler patent referred to hereinbefore. onsequently, any current which is supplied to the wheels and axle by the transformer E will provide an increased retardation over that obtained with the usual eddy current brake.

One advantage of apparatus embodying my invention is that the retardation due to the current supplied to the Wheels and axles is independent of the speed of the car.

Although I have herein shown and de scribed only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A railway car retarder comprising means for passing magnetic flux through a car wheel in a direction parallel to the axle, and means for passing electric current through said wheel in a path perpendicular to the path of such flux and in such direction as to enact with the flux to retard the move ment of the car.

2. A railway car retarder comprising a U- shaped electromagnet located in the track way with its legs on opposite sides of a rail and its pole pieces in positions to coact with the opposite faces of a car Wheel mov ing along such rail, and means for passing electric current through such car wheel in a direction perpendicular to the path of the flux produced in the wheel by said electromagnet.

3. A railway car retarder comprising means for passing magnetic flux through a car wheel in a direction parallel to the axle, and a source of electric current connected across the rails of the track traversed by the car for causing current to flow through the Wheels and axles of the car in such direction as to coact with such magnetic flux to retard the movement of the car;

4. A railway car retarder comprisingtwo oppositely located U-shaped electromagnets associated with'the two rails of a track respectively and each having its legs disposed on opposite sides of the associated rail and its pole pieces in positions to coact with the opposite faces of a Wheel moving along the rail, and a source of electric current connected across said rails in such direction that when a pair of car wheels passes through said magnets the current which flows through such wheels and the associated axle coacts with the magnetic flux produced in the wheels by the magnets to retard the movement of the car.

' In testimony whereof I aflix my signature.

PAUL H. CRAGO. 

